Schizophrenia As A Genetic Disorder

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Jade Flint

Discuss the view that schizophrenia is a genetic disorder. (30)

The fact that schizophrenia has been found to run in families has led to the inference that it has a genetic basis. According to the genetic hypothesis, the closer related the family member to the schizophrenic the greater the chance of developing schizophrenia. However, experts do agree that if anything is inherited in schizophrenia, it is a genetic predisposition to develop the disease rather than a certainty.

Evidence supporting the genetic basis of acquiring schizophrenia comes from family studies. These show that the risk of developing schizophrenia is greater for those more closely related to the schizophrenic. This is supported by Gottesman who found that if both parents have schizophrenia there is a 46% chance of developing the disease, if a single parent has schizophrenia there is a 16% chance and if a sibling has schizophrenia there is an 8% chance. In addition to this there is also a 17% chance of developing schizophrenia in families where the identical twin of one parent has schizophrenia – this shows the influence of nature over nurture. However, the fact that concordance rates increase with genetic relatedness may be explained by the fact that this is because they are also likely to spend more time together, which means environmental factors may be influential, maybe more so than genetic. Also, fewer than 50% of children where both parents have schizophrenia develop the disorder, which is evidence against a direct genetic link.

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Further research into genetic links has been conducted by Sherrington, in the form of gene-mapping studies. Sherrington found that there is a gene located on chromosome 5 that has been linked to schizophrenia in a small number of extended families where a number of family members had the disorder. However, further research into the gene on chromosome 5 has failed to replicate Sherrington’s findings and so reliability is low. Kennedy suggested that the validity of the research is questionable as the findings may be only representative of the original sample.

Gottesman conducted further research into the concordance rates ...

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